Brass is being utilized in different areas of mechanical engineering, electrical engineering and sanitation technology.
The components in mechanical engineering and in electrical engineering are becoming increasingly smaller and more filigree due to the trend toward miniaturization. Also, components of brass are often connected with other metallic and non-metallic materials to form complicated groups of components. However, both make a recycling of the materials based on a separation or division more difficult.
Further difficulties occur in particular when the components to be recycled contain toxic or health-threatening elements or substances. These can directly endanger the workers in a factory which produces and processes these materials. An environmental impact is created when these materials must be stored for a prolonged period of time and are thereby subjected to atmospheric influences. In addition, the toxic substances may contaminate the accessory agents, for example, the separating means, which are utilized during the preparation of shredder fractions via the sinking or floating method. An expensive waste disposal of the accessory agents would then be needed. Of course health-threatening substances and elements are also undesired during the use of the components if an emission into the environment or the living organism cannot be completely avoided.
Thus, a composition which is non-threatening with respect to ecological and toxic reasons is important for such products. The increased concerns about the environment, which can be found in many standards and technical controls, for example the re-enacted drinking-water regulation DIN 50930-6 or the scrap-material regulation, demands suitable materials.
The field of electrical engineering utilizes mainly Pb-containing brass as a contact material, namely as stationary contacts or solid contacts, part of which are, for example, clamping joints and plug connectors or connector contacts. When choosing the material, its easy processing stands in the foreground. The respective componentry can be manufactured with a high degree of productivity out of a machinable Pb-containing brass.
The Pb particles in the structure create disadvantages. The particles act as chip breakers and reduce the strength or ductility of the material due to a notching tendency and reduction of the load-bearing cross-section. These disadvantages must be compensated for by suitably dimensioning the component.
All fastening elements have, caused by their manufacture, a more or less inherently high mechanical stress. These are often superposed by tensile-load tensions which are caused by screw connections. When the clamping joints are manufactured out of common Pb-containing brass, there exists, due to such tensions, a great danger for tension stress corrosion cracking.
In addition, there also exists a need for ecologically compatible materials in the field of electrical engineering. Looking at the directives given by the European Parliament regarding the electrical and electronic apparatus used, it can be seen that, within a reasonably short period of time in the future, Pb will become an undesired alloy part. The goal of this initiative is, in this connection, to increase the portion of environmentally friendly materials in the material cycle.
Furthermore, components or containers for the transport or the storage of liquids are made out of Pb-containing brass. An important area is the sanitation technology. Negligence regarding the metal is especially particularly problematic here. The materials being used should thus be hardly susceptible to any type of corrosion. The components for the transport or the storing of liquids are as a rule manufactured by machining. A hot forming via die-forging often precedes.
These lead-containing brass alloys are known, for example, from the Reference DE 43 18 377 C2, which are used as a malleable or casting alloy in the optic industry, the jewelry industry and in the area of drinking water and sanitation installation. This alloy also achieves its good machining ability from an admixture of a considerable amount of lead.
The further development of easily machinable lead-free malleable alloys based on copper is known from the Reference DE 691 24 835 T2. The alloy is supposed to replace present lead-containing materials without changing the processing conditions. Instead of lead, bismuth and the elements phosphor, indium and tin are added in small amounts for this purpose to the alloy.
The basic purpose of the invention is to provide an improved lead-free copper alloy with respect to its characteristics and to set forth its use.